With the growing interest in environmental problems and energy depletion, solar energy is drawing increasing attention as alternative energy that is abundant, free from problems of environmental contamination, and highly efficient.
Solar energy may be classified into solar thermal cells that generate vapor necessary for rotating a turbine using solar heat and into photovoltaic cells that convert sunlight into electric energy using the properties of a semiconductor.
To form a photovoltaic cell, a photoelectric element that converts light into electricity is essential. A photodiode, a type of photoelectric element, uses mono-crystals such as silicon (Si) or gallium arsenide phosphide (GaAsP) and uses a PN junction or a PIN junction.
For the photodiode, it is very important to increase the efficiency of converting incident sunlight into electric energy is very important. Therefore, research is being continuously conducted on the structure and material of the photodiode.